fiberglass

[jeepurze]

Im fixin to make some fiberglass tails cowells, ive tried alum and dont have the skill or tools to get curves I want, so I made a frame outa 1/4 in pine plywood, and ive put four layers on it, now between coats I rough sanded smooth but on the finish or top layer what sand paper should i start with? wet sand? also will fiberglass bondo attatch to it? Ive only used glass on old jeep floorboards that didnt have to finished smooth so I only know basics. these are practice runs for a future xs streetfighter so Ill make a couple n see.

[spyug]

Jeep,
Getting a smooth surface on fiberglass can be easy or a royal pain. Doing it the way you are, you have a couple of choices. What I would do is first sand the surface as smooth as you can with progressive course (80/100 grit to 600 grit wet dry) to fine). Next ( if possible) spray on several coats of resin sanding between to build up the gelcoat. If spraying is not possible use a roller but don't over load the resin or it will run creating more problems to deal with. Level everything out with thinly spread bondo. Sand again with medium grits down to fine. Fill scratches with surface filler or primer surfacer. Sand as smooth as you can with 600 w/d to 1500 w/d ( if time is not an issue).

As with any blocking job use sanding blocks to keep from crating an uneven surface.

If the existing surface is relatively flat, you can skip the extra resin coats and go straight to bondo. With resin and Bondo always sand between coats to give grip to the layers.

Just a word of caution. If the resin has not thoroughly penetrated the cloth ( leaving dry patches) or if you have air bubbles, you will need to cut these out and re resin first. Also do not sand so hard that you break through the resin as you will then take all the strength out of the layup.

With glassing, take your time.....don't rush.



Good luck,
spyug.

Ps. I've talked about this before but if you are looking for an easy way to do a seat, use the fiberglass over foam method for the lightest strongest seats. Remember BMX in Indonesia he did his that way after I suggested it. Easy to do. The only difference to regular glassing is the resin which must be Epoxy which will not eat the foam regular f/g resin will destroy foam in seconds.

Use regular house insulation pink or blue foam ( not white..not dense enough) to make the buck. Glue sheets toghether to make a block cut and sand to the finish shape you want. Mix up some epoxy ( usually a two part resin and hardner combo). Paint the whole buck with it. Let it cure, now you have a rigid core. Use fine fiberglass cloth laid over the buck and paint on with more epoxy. It is easiest to cut and do sections. You can hold the cloth in place with push pins. Do the top first, then the bottom. One layer of cloth is all that is necessary but add a second if you like. For second coats and more you can use regular glass resin which is cheaper than epoxy, just be sure the whole thing is sealed in epoxy first and there are no gaps that will let the glass resin in ( to melt the foam).

With the foam core you have ease of shaping, rigidity and it is lighter than a wood core and just as strong. My tracker seat is done this way with one layer of cloth. I'm about 200 pounds with all my gear and I've been bouncing around on it now for two months with no sign of problems.

Give it a try.

Spyug.

[jeepurze]

jezz forgot about the foam thanks Ill do the second one that way. im just experimenting with the shape for now. thanks for the tips.

[82bobber]

a later response, spyug has given all the best info, just wanted to throw in an experience when i was a kid, my dad and uncle built a catamaran plaster mold, upside down hull, shaped plaster over wood buildt form covered chicken wire frame, than plastered and sanded and plastered etc, then waxed it, covered with heavy f/g weave and then popped off a female mold to make males out of, multple production type mod. ...just a thought in case ya want to go in bizness.

[jack]

OK Spyug and 82 Bobber,now ya got me thinking again about my roaster seat ;D How exactly do I go about making a mold for fiber glassing or using carbon fiber.............Jack

[spyug]

Jack,
The easiest & cheapest way to make a mold I think would be to use the pink foam as I have suggested for the plug. Make it exactly as you would like the finished seat to be. Shape and smooth the foam as fine as you can.

As 82B mentions, coat the plug with Plaster of Paris, joint compound, plasterers mud or whatever you call it and let it dry thoroughly. Sand as smooth as you can with progressively finer grits. Get it as smooth as you can. Don't let any cracks appear or any of the foam to show.

When as smooth as possible coat with several good applications of a carnuba based wax. The wax will act as the release agent.

Now get enough ( 1/2 yard maybe) 4 ounce or lighter glass cloth and an equal amount of "woven roving" and or glass mat ( short strands compressed into a matting) enough to cover the plug in one application. You may also want to make some "ribs" from cardboard, press board or thin plywood to stiffen the mold. Cut two or three to the contour s of the seat/tail.

Get a nice big piece of cardboard and lay the plug on it. Mix up a batch of the resin and paint on to the plug. This is the gelcoat which is the surface of the mold ( i.e. female of the plug). Make sure the resin covers all of the plug and as even as you can get it. You may want to experiment first with mixing the resin as you want it to be somewhat liquid and easy to spread but not runny like water and not so thick that is sets up in only a few minutes. There are so many different types of cloths and resin materials you might want to talk with someone in the trade maybe at a boat yard or plastics retailer if any in your area.

With the gelcoat still tacky, mix another batch of resin, drape the plug with the fine cloth and apply the resin to the cloth, Everything should appear wet. Any white spots or bubbles need to be worked out. The ends of the cloth can be pinned down to the cardboard. With the resin still tacky on the mold add the woven roving and or glass cloth. This will give substance to the mold. Use the "ribs" for rigidity and fix them to the mold with strips of cloth and more resin.

Depending on the resin type the mold should be allowed to cure at room temperature ( 70) for 12 to 24 hours. Once cured pull the mold off the plug ( pry it off with wooden wedges or if necessary destroy the plug).

Hopefully the mold will come out smooth and not too much more will be necessary.Sand with wet and dry papers from 600 grit down to 1500 grit. The idea is to get it "glass" smooth and remember any imperfections in the mold will show up on the finished product. Fill any cracks or holes with more resin.

Once it is smooth as a babies bum, wax her up, she is ready to go. Paint or spray on your gelcoat ( you can get special resins for this that can be or are impregnated with colour). Lay in your fine mesh cloth and add more resin. Add a layer of roving or mat for rigidity. Allow to cure and pop free. if you find the seat is not rigid enough or if you want to add attachment points or devices you can glass them in to the underside...just rough up the cured fiberglass with some medium grit sandpaper to give the next resin coat a "tooth " to bond to.

This is a very simple explanation of the procedure but there are lots of illustrations all over the net. Read up on anything in home built boats or planes. Lots of good stuff.

One thing to remember about mold design and making is that the plug and later the finished product need to come free of the mold when cured. The top edges of the mold must be 90% ( on the vertical) or better, anything less and the product won't come free. Also resin shouldn't be allowed to set over the edge of the mold for the same reason.

For making duplicates of the same product , molds are probably best. For one offs however, I find the glass over foam to be easier and quicker.

Do some reading and research then grab some cloth and resin and have at it. Just remember to keep safety in mind, gloves, goggles, respirators etc........you know the drill.

Let us know what you get up to.

Cheers,
spyug.

[jack]

DANG!!!!!!!!!!! Spyug,I can't thank you enough for that solid information.THANK YOU THANK YOU THANK YOU THANK YOU THANK YOU.Is that enough or should i continue? ;D....Jack

[jeepurze]

jack said:

DANG!!!!!!!!!!! Spyug,I can't thank you enough for that solid information.THANK YOU THANK YOU THANK YOU THANK YOU THANK YOU.Is that enough or should i continue? ;D....Jack

yup here too jack, it would also explain why my fiberglassing looks like demented carbon fibre gone bad.

[jack]

Jeepurze...............getting it down pat comes from repeated cycles ;D.................Jack

[jeepurze]

ive got a few articles saved on this but he managed to explain it in one large paragraph and i understand it, amazing as there no pic, DUDE WRITE A BOOK. and if ya got any links on materials let me know , its good to hear it from people that actually know what their talkin about , thanks again, jeep.

[spyug]

Guys,
Thanks for all the kind words but I merely scratched the surface. Just wait 'til we talk about vacuum bagging and other advanced techniques. For now this is one of the better articles on the glass over foam technique :

homepages.paradise.net.nz/garyd/quikama.html Its about out rigger floats but gives you a very good idea of how its done.

This is the best epoxy and associated products to use IMHO :

www.westsystem.com/.

There are many other types and if you speak with a good automotive or marine paint and products supplier, they should be able to put you on to other types. Epoxy resins ( polyurethanes) are more pricey than standard resins ( vinyl esters and polyesters) but as I mentioned, you can coat your foam plugs with a "paint" coat of epoxy and glass over in normal resin to lessen the cost. As long as the foam is sealed the standard resin will not destroy it.

Another technique I heard of but haven't yet tried is to wrap the plug in packaging tape ( 2 or 3 inch wide) and glass over that. It eliminates the need for epoxy. I am going to build a seat for the Virago so I'll try that method and let you know how it goes.

I find the hardest part of glassing a plug or any glassing project for that matter is the prep. Get the plug finished as smooth as you can, cut and trial fit the glass cloth and have lots of containers ready to make your batches of resin. Make small batches and make more as you need it. Resin will go a long way, just be sure to work it in to the glass (to saturate it) With the epoxy resin it is easiest to mix as there are 2 parts and they need to be mixed to formula (1:1 or 2:1 or some such). Ester resins are a bit more of a problem for new users as getting the ratio of hardener to resin is not always clearly spelled out and ( like Bondo) too much hardener and she sets up before you can use it all. Too little and it takes a year to cure. Trial and error guys.

Once you get the hang of it glassing can be fun and what you can create is only limited by your imagination.

Have at it guys and lets see what you come up with.

Cheers,
Spyug

[jeepurze]

thanks man , you dont know how much this helps me.

[jeepurze]

question , if ive got an unusual shape do I make relieve cuts in the dry glass, (this is habit ive done carpeting my whole life and put it on everything imaginable) so say its a dome shape lay it on dry make relieve cuts, jezz hope ya know what I mean.

[bill letson]

would just like to make a couple of quick points.two things to considerwhen fiberglassing.1 epoxy will bond to polyester resinwith no problem but polyester does not bond well to epoxy.2 fiberglass is made differently for both products.polyester resin is made with styrene and the binder in the glass for polyester is made to breakdown with styrene.epoxy does not use styrene,so it takes a different glass.i know some people will say that they intermixed these products with no problems,and that may be true but they beat the odds.my feeling is better safe than sorry.using just epoxy is cheaper if you only have to make it once.i have 30+years of boat building and repair experiance in the marine industry so i'm a little bit familiar with the products.

[82bobber]

I was searching over on another site about trikes, and there is a builder who makes the complete trike body outta cardboard and then fiberglasses over the cardboard to make the body section....seems it would sag if it got too wet, but I guess getting the right set time on the resin and support would be the ticket...juz some info.